Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/itertools.pyi

@@ -0,0 +1,111 @@
+import sys
+from typing import Any, Callable, Generic, Iterable, Iterator, Optional, Tuple, TypeVar, overload
+from typing_extensions import Literal
+
+_T = TypeVar("_T")
+_S = TypeVar("_S")
+_N = TypeVar("_N", int, float)
+Predicate = Callable[[_T], object]
+
+def count(start: _N = ..., step: _N = ...) -> Iterator[_N]: ...  # more general types?
+
+class cycle(Iterator[_T], Generic[_T]):
+    def __init__(self, __iterable: Iterable[_T]) -> None: ...
+    def __next__(self) -> _T: ...
+    def __iter__(self) -> Iterator[_T]: ...
+
+@overload
+def repeat(object: _T) -> Iterator[_T]: ...
+@overload
+def repeat(object: _T, times: int) -> Iterator[_T]: ...
+
+if sys.version_info >= (3, 8):
+    @overload
+    def accumulate(iterable: Iterable[_T], func: None = ..., *, initial: Optional[_T] = ...) -> Iterator[_T]: ...
+    @overload
+    def accumulate(iterable: Iterable[_T], func: Callable[[_S, _T], _S], *, initial: Optional[_S] = ...) -> Iterator[_S]: ...
+
+else:
+    def accumulate(iterable: Iterable[_T], func: Optional[Callable[[_T, _T], _T]] = ...) -> Iterator[_T]: ...
+
+class chain(Iterator[_T], Generic[_T]):
+    def __init__(self, *iterables: Iterable[_T]) -> None: ...
+    def __next__(self) -> _T: ...
+    def __iter__(self) -> Iterator[_T]: ...
+    @staticmethod
+    def from_iterable(__iterable: Iterable[Iterable[_S]]) -> Iterator[_S]: ...
+
+def compress(data: Iterable[_T], selectors: Iterable[Any]) -> Iterator[_T]: ...
+def dropwhile(__predicate: Predicate[_T], __iterable: Iterable[_T]) -> Iterator[_T]: ...
+def filterfalse(__predicate: Optional[Predicate[_T]], __iterable: Iterable[_T]) -> Iterator[_T]: ...
+@overload
+def groupby(iterable: Iterable[_T], key: None = ...) -> Iterator[Tuple[_T, Iterator[_T]]]: ...
+@overload
+def groupby(iterable: Iterable[_T], key: Callable[[_T], _S]) -> Iterator[Tuple[_S, Iterator[_T]]]: ...
+@overload
+def islice(__iterable: Iterable[_T], __stop: Optional[int]) -> Iterator[_T]: ...
+@overload
+def islice(
+    __iterable: Iterable[_T], __start: Optional[int], __stop: Optional[int], __step: Optional[int] = ...
+) -> Iterator[_T]: ...
+def starmap(__function: Callable[..., _S], __iterable: Iterable[Iterable[Any]]) -> Iterator[_S]: ...
+def takewhile(__predicate: Predicate[_T], __iterable: Iterable[_T]) -> Iterator[_T]: ...
+def tee(__iterable: Iterable[_T], __n: int = ...) -> Tuple[Iterator[_T], ...]: ...
+def zip_longest(*p: Iterable[Any], fillvalue: Any = ...) -> Iterator[Any]: ...
+
+_T1 = TypeVar("_T1")
+_T2 = TypeVar("_T2")
+_T3 = TypeVar("_T3")
+_T4 = TypeVar("_T4")
+_T5 = TypeVar("_T5")
+_T6 = TypeVar("_T6")
+@overload
+def product(__iter1: Iterable[_T1]) -> Iterator[Tuple[_T1]]: ...
+@overload
+def product(__iter1: Iterable[_T1], __iter2: Iterable[_T2]) -> Iterator[Tuple[_T1, _T2]]: ...
+@overload
+def product(__iter1: Iterable[_T1], __iter2: Iterable[_T2], __iter3: Iterable[_T3]) -> Iterator[Tuple[_T1, _T2, _T3]]: ...
+@overload
+def product(
+    __iter1: Iterable[_T1], __iter2: Iterable[_T2], __iter3: Iterable[_T3], __iter4: Iterable[_T4]
+) -> Iterator[Tuple[_T1, _T2, _T3, _T4]]: ...
+@overload
+def product(
+    __iter1: Iterable[_T1], __iter2: Iterable[_T2], __iter3: Iterable[_T3], __iter4: Iterable[_T4], __iter5: Iterable[_T5]
+) -> Iterator[Tuple[_T1, _T2, _T3, _T4, _T5]]: ...
+@overload
+def product(
+    __iter1: Iterable[_T1],
+    __iter2: Iterable[_T2],
+    __iter3: Iterable[_T3],
+    __iter4: Iterable[_T4],
+    __iter5: Iterable[_T5],
+    __iter6: Iterable[_T6],
+) -> Iterator[Tuple[_T1, _T2, _T3, _T4, _T5, _T6]]: ...
+@overload
+def product(
+    __iter1: Iterable[Any],
+    __iter2: Iterable[Any],
+    __iter3: Iterable[Any],
+    __iter4: Iterable[Any],
+    __iter5: Iterable[Any],
+    __iter6: Iterable[Any],
+    __iter7: Iterable[Any],
+    *iterables: Iterable[Any],
+) -> Iterator[Tuple[Any, ...]]: ...
+@overload
+def product(*iterables: Iterable[_T1], repeat: int) -> Iterator[Tuple[_T1, ...]]: ...
+@overload
+def product(*iterables: Iterable[Any], repeat: int = ...) -> Iterator[Tuple[Any, ...]]: ...
+def permutations(iterable: Iterable[_T], r: Optional[int] = ...) -> Iterator[Tuple[_T, ...]]: ...
+@overload
+def combinations(iterable: Iterable[_T], r: Literal[2]) -> Iterator[Tuple[_T, _T]]: ...
+@overload
+def combinations(iterable: Iterable[_T], r: Literal[3]) -> Iterator[Tuple[_T, _T, _T]]: ...
+@overload
+def combinations(iterable: Iterable[_T], r: Literal[4]) -> Iterator[Tuple[_T, _T, _T, _T]]: ...
+@overload
+def combinations(iterable: Iterable[_T], r: Literal[5]) -> Iterator[Tuple[_T, _T, _T, _T, _T]]: ...
+@overload
+def combinations(iterable: Iterable[_T], r: int) -> Iterator[Tuple[_T, ...]]: ...
+def combinations_with_replacement(iterable: Iterable[_T], r: int) -> Iterator[Tuple[_T, ...]]: ...